rust: rust_is_available: warn for `bindgen` < 0.72.1 && libclang >= 22

index 551f1ebd0dcb..c30983562a2f 100755
@@ -208,6 +208,20 @@ if [ "$bindgen_libclang_cversion" -lt "$bindgen_libclang_min_cversion" ]; then
 	exit 1
 fi
 
+if [ "$bindgen_libclang_cversion" -ge 2200000 ] &&
+	[ "$rust_bindings_generator_cversion" -lt 7201 ]; then
+	# Distributions may have patched the issue.
+	if ! "$BINDGEN" $(dirname $0)/rust_is_available_bindgen_libclang_22.h | grep -q 'pub foo'; then
+		echo >&2 "***"
+		echo >&2 "*** Rust bindings generator '$BINDGEN' < 0.72.1 together with libclang >= 22"
+		echo >&2 "*** may not work due to a bug (https://github.com/rust-lang/rust-bindgen/pull/3278)."
+		echo >&2 "***   Your bindgen version:  $rust_bindings_generator_version"
+		echo >&2 "***   Your libclang version: $bindgen_libclang_version"
+		echo >&2 "***"
+		warning=1
+	fi
+fi
+
 # If the C compiler is Clang, then we can also check whether its version
 # matches the `libclang` version used by the Rust bindings generator.
 #

index d6d54b7ea42a..e14cf2c5695e 100755
@@ -54,16 +54,23 @@ else:
 """)
 
     @classmethod
-    def generate_bindgen(cls, version_stdout, libclang_stderr):
+    def generate_bindgen(cls, version_stdout, libclang_stderr, libclang_22_patched=False):
         if libclang_stderr is None:
             libclang_case = f"raise SystemExit({cls.bindgen_default_bindgen_libclang_failure_exit_code})"
         else:
             libclang_case = f"print({repr(libclang_stderr)}, file=sys.stderr)"
 
+        if libclang_22_patched:
+            libclang_22_case = "print('pub foo: ::std::os::raw::c_int,')"
+        else:
+            libclang_22_case = "pass"
+
         return cls.generate_executable(f"""#!/usr/bin/env python3
 import sys
 if "rust_is_available_bindgen_libclang.h" in " ".join(sys.argv):
     {libclang_case}
+elif "rust_is_available_bindgen_libclang_22.h" in " ".join(sys.argv):
+    {libclang_22_case}
 else:
     print({repr(version_stdout)})
 """)

@@ -248,6 +255,27 @@ else:
         result = self.run_script(self.Expected.FAILURE, { "BINDGEN": bindgen })
         self.assertIn(f"libclang (used by the Rust bindings generator '{bindgen}') is too old.", result.stderr)
 
+    def test_bindgen_bad_libclang_22(self):
+        for (bindgen_version, libclang_version, expected_not_patched) in (
+            ("0.71.1", "21.1.0", self.Expected.SUCCESS),
+            ("0.71.1", "22.0.0", self.Expected.SUCCESS_WITH_WARNINGS),
+            ("0.71.1", "22.1.0", self.Expected.SUCCESS_WITH_WARNINGS),
+
+            ("0.72.0", "22.0.0", self.Expected.SUCCESS_WITH_WARNINGS),
+
+            ("0.72.1", "22.0.0", self.Expected.SUCCESS),
+        ):
+            with self.subTest(bindgen_version=bindgen_version, libclang_version=libclang_version):
+                cc = self.generate_clang(f"clang version {libclang_version}")
+                libclang_stderr = f"scripts/rust_is_available_bindgen_libclang.h:2:9: warning: clang version {libclang_version} [-W#pragma-messages], err: false"
+                bindgen = self.generate_bindgen(f"bindgen {bindgen_version}", libclang_stderr)
+                result = self.run_script(expected_not_patched, { "BINDGEN": bindgen, "CC": cc })
+                if expected_not_patched == self.Expected.SUCCESS_WITH_WARNINGS:
+                    self.assertIn(f"Rust bindings generator '{bindgen}' < 0.72.1 together with libclang >= 22", result.stderr)
+
+                bindgen = self.generate_bindgen(f"bindgen {bindgen_version}", libclang_stderr, libclang_22_patched=True)
+                result = self.run_script(self.Expected.SUCCESS, { "BINDGEN": bindgen, "CC": cc })
+
     def test_clang_matches_bindgen_libclang_different_bindgen(self):
         bindgen = self.generate_bindgen_libclang("scripts/rust_is_available_bindgen_libclang.h:2:9: warning: clang version 999.0.0 [-W#pragma-messages], err: false")
         result = self.run_script(self.Expected.SUCCESS_WITH_WARNINGS, { "BINDGEN": bindgen })